Examination of how the brain mediates emotional experience is now an area of significant and intense research interest. This is an important endeavour considering that emotion is a key component in vulnerability factors governing risk for mood and anxiety disorders. Recent neuropsychological and neuroimaging studies are also beginning to explore the effects of antidepressants on the processing of emotional stimuli in healthy participants to help understand the role of neurochemicals in affective behaviour more broadly. Unfortunately the literature is fraught with contradictions and complications resulting from the technique used, task instructions, selection of stimuli and gender differences. The aim of the current thesis therefore, was to investigate emotional processing in healthy participants and to examine the impact of serotonergic augmentation on this processing through the presentation of visual emotional stimuli and examination of self report, peripheral- and neurophysiological measures of emotional responsiveness. Seventy five images low in arousal content, selected from the International Affective Picture System (IAPS) and categorised as pleasant, neutral and unpleasant, were presented to participants in four experimental studies. Findings support previous literature suggesting that there is substantial overlap in frontal neural circuitry when the brain processes emotional images of different valence. Gender differences in the processing of visual emotional stimuli were also observed however suggesting the need for future studies to take such factors into account. In particular, females unlike males displayed right-sided, frontal, neurophysiological activations in response to unpleasant relative to neutral images. Emotional valence was also found to modulate heart rate (HR) thereby confirming the reliability and validity of the task-viewing paradigm. Augmentation of serotonin was found to suppress any differences in HR across the three differently valenced categories of images, while neurophysiological responses were potentiated during pleasant valence but suppressed during unpleasant valence. In summary, the studies included in this thesis provide evidence for neurophysiological modulation by emotional content and gender. In addition, the studies employ a more systems-based approach to the study of antidepressant action, through examination of the neurophysiological responses to visual emotional stimuli. This approach may lead to greater understanding of the functional consequences of neurochemical modulation on cortical networks involved in emotional processing.